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COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Thomas Pfeiffer, Frank Schaich - Alcatel-Lucent Bell Labs Stuttgart OFC/NFOEC wireless backhauling.

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Presentation on theme: "COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Thomas Pfeiffer, Frank Schaich - Alcatel-Lucent Bell Labs Stuttgart OFC/NFOEC wireless backhauling."— Presentation transcript:

1 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Thomas Pfeiffer, Frank Schaich - Alcatel-Lucent Bell Labs Stuttgart OFC/NFOEC wireless backhauling workshop - Los Angeles, OPTICAL ARCHITECTURES FOR MOBILE BACK- AND FRONTHAULING

2 2 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Backhauling or fronthauling ? EPC : Evolved Packet Core BBU : Baseband Unit RAN : Radio Access Network IP backhaul or CPRI fronthaul ? = conventional RAN or cloud RAN ? … most likely both of them core network metro cell (200 m diam.) EPC centralized BBU IP backhaul CPRI fronthaul macro cell (1 km diam.) IP backhaul conventional RAN cloud RAN

3 3 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Fiber transmission systems protocol :IP, CPRI, others (digital; RoF not considered here) direct or over PON, Ethernet, … multiplexing : TDM, WDM, TWDM, … topology : ptp, ptmp, ring architecture: dedicated ? overlay ? shared with FTTx ? Metrics technical metrics : ­bandwidth (scaleability, user statistics), latency, jitter ­environmental factors : temperature, humidity, mechanical ­location factors : availability of local powering, footprint, accesseability economic metrics : ­infrastructure : ownership, availability of dark fibers, digging cost, leasing cost, opportunity for sharing ­location factors : power supply and power consumption, rights of way Choice of transmission technology : optical only

4 4 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Backhauling and fronthauling bandwidth in LTE IP backhauling = variable bitrate - antennas may be grouped (e.g. beamforming) : each group counts as one single element - user traffic statistics apply : - shown above are achievable peak rates on air i/f - avged. values may be less by an order of mag IP backhauling = variable bitrate - antennas may be grouped (e.g. beamforming) : each group counts as one single element - user traffic statistics apply : - shown above are achievable peak rates on air i/f - avged. values may be less by an order of mag CPRI fronthauling = constant bitrate - each antenna counts separately (individual streams) - 8B/10B can be removed for transport over Ethernet - compression can be applied to reduce to 1:3 CPRI fronthauling = constant bitrate - each antenna counts separately (individual streams) - 8B/10B can be removed for transport over Ethernet - compression can be applied to reduce to 1:3 IP peak bandwidth per site typ. for macro cell CPRI bandwidth per site * 8/15 in case of WCDMA typ. for macro cell

5 5 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Backhaul and fronthaul network dimensions and architecture shall account for traffic statistics traffic statistics per cell statistical multiplex gain on IP backhaul variations of total cell traffic over the day load sharing (pooling gain) in cloud RAN Impact from traffic statistics taken from Alcatel-Lucent Technology lightRadio TM White Paper Economic analysis (2011)

6 6 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Latency in LTE : limited by synchronous UL HARQ n Orig. TX n+4 n+8 NACK 1 st RTX UEeNB t [ms] 3 msec fixed delay defined by LTE standard eNB processing 1. PHY: UL frame decoding 2. MAC: ACK/NACK creation 3. PHY: DL frame creation t [ms] n Orig. TX n+4 n+8 NACK 1 st RTX UEeNB reduced time for eNB processing t [ms] RRH round trip time (10 µsec / km) + transport system processing time t [ms] The allowed RRH eNB t ransmission time is limited to <<1 msec It comes at the expense of a reduced processing time in the eNB

7 7 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Serving area around traditional CO 32 macro cells, backhauled by single dedicated 10G-PON - peak rate = 10Gbps per site; sufficient even for extreme loads - average rate = 320 Mbps per site can be increased by using multiple 10G-PONs, WDM-stacked - link length = 20 km reaches any site within the area over realistic cable routes Possible migration towards serving from consolidated Super-CO via WDM stacking : hybrid WDM/TDM long reach 10G-PONs (cf. PIEMAN, MUSE, SARDANA for example architectures + upcoming NGPON2 standardisation for specs (tbd) ) IP backhaul by 10G-PON : urban area, macro cells max. 20 km power splitter Central Office power splitter eNBs 1 4 Router OLT ONT CO serving area: diam. 6 km macro cell: diam. 1 km

8 8 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Scenario: serving area around CO with -32 macro cells: 10G peak / 320M avge. 10G-PON, 1:32 split (3 sectors * 8 antennas * 100 MHz) (XGPON1 or XGPON2) -16 metros per macro : 1.7G peak / 26M avge. 8 x GPON, 1:64 split each (1 sector * 4 antennas * 100 MHz) (stacking via low cost WDM) low cost WDM-PON by cyclic wavelength allocation within 40 nm band cf. Pöhlmann, Pfeiffer: ECOC 2011, paper We.9.C.1 IP backhaul (ctd) : urban area, macro + metro cells CO serving area: diam. 6 km macro cell: diam. 1 km metro cells max. 20 km hybrid splitter: 10G - power splitter GPON - cyclic AWG Central OfficeeNBs metro (8 x 64) macro (32 x) 10G-PON GPON macro area dipl exer power splitter 10G + j GPON power splitter 1 4 Router WDM1r (diplexer) GPON #1 … #8 10G PON cyclic AWG OLTs

9 9 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. BBU clustering : move BBU hardware from BTS into common central space ­simplified hardware at antenna sites (footprint, electrical power) and in BBU (indoor specs) ­zero latency links between BBUs allow for implementing CoMP and ICIC algorithms BBU pooling : share hardware elements between multiple colocated BBUs ­additional benefit : ease of load-sharing between clusters Either variant requires CPRI links to remote antenna sites ­transmission bandwidths easily reach levels that render TDM-PON unattractive ­small split factors (1:2 or 1:4) ­constant bitrate, i.e. no statistical multiplex gain ­strict latency limits (<<1 msec) require zero framing/buffering etc. delays ­most viable solutions employ ptp-links via ­fiber, if available … ­wavelength : ptp-WDM overlay on TDM-PON or pure WDM-PON Centralized processing : variants and benefits

10 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. CPRI fronthaul via WDM overlay on LR-PON (ACCORDANCE project) MCO … Metro Central Office RN … remote node

11 11 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Enable BBU pooling, but not via CPRI : alternatives increased optical link bandwidth - simpler remote unit - possible pooling gains IP backhauling split within L1 CPRI fronthauling split within L2

12 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

13 Back-Up

14 14 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. Conventional Approach Example XG-PON1 upstream, 4 Wavelength Subbands SB1 – SB4 DFB laser wavelength can be tuned by heating or cooling by 0.08nm/K. Tuning range up to 3nm. SB2 SB1 SB3 SB4 1260nm 1265nm 1270nm 1275nm 1280nm Wavelength band is separated in four subbands for wavelength stacking Randomly distributed DFB laser wavelengths in the 20nm band

15 15 COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. TWDM 40/10G with ultra-low cost WDM upstream (ALU proposal, ECOC 2011) wavelength sets Downstream : 4 x 10G TDM DWDM channels, 100GHz spacing, nm band - OLT : -stabilised DFB transmitter - ONU : FP based tunable filter Upstream : 4 x 2.5G TDMA wavelength sets, 50GHz grid, nm band - OLT : filtered with cylical AWG - ONU : partially tunable DFB with integrated heater WSDM (wavelength set division multiplexing) Operational principle: - cyclic optical filter at Rx, 50 or 100 GHz grid - narrow range Tx tuneability instead of full band - accomplished by integrated heater stripe (no TEC) - otherwise conventional transmitter technology

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